Thrombocytopenia as a marker of liver steatosis in a low-endemic
area for schistosomiasis mansoni
ALBA OTONI1, CARLOS MAURICIODE FIGUEIREDO ANTUNES2, FERNANDA FERREIRA TAVARES3, DÉBORA HELOÍSA QUADROS ARAÚJO4,
THIAGODE ALMEIDA PEREIRA1, LEONARDO CAMPOSDE QUEIROZ5, FREDERICO FIGUEIREDO AMÂNCIO6, JOSÉ ROBERTO LAMBERTUCCI7*
1PhD in Health Sciences, Department of Infectology and Tropical Medicine, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil 2PhD in Epidemiology, Department of Epidemiology, Instituto de Ensino e Pesquisa da Santa Casa de Belo Horizonte, Belo Horizonte, MG, Brazil 3MSc in Health Sciences, Department of Infectology and Tropical Medicine, UFMG, Belo Horizonte, MG, Brazil
4Nursing Student, Undergraduate Program, Universidade Federal de São João del-Rei, São João del-Rei, MG, Brazil 5MD, Radiologist. PhD in Health Sciences, Department of Infectology and Tropical Medicine, UFMG, Belo Horizonte, MG, Brazil 6PhD in Infectious Diseases and Tropical Medicine; MD, Infectious Disease Physician, Belo Horizonte, MG, Brazil 7PhD in Infectious Diseases and Tropical Medicine; MD, Professor at UFMG, Belo Horizonte, MG, Brazil
S
UMMARYStudy conducted at the Department of Infectology and Tropical Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
Article received: 12/1/2016
Accepted for publication: 12/19/2016
*Correspondence:
Departamento de Infectologia e Medicina Tropical – UFMG Address: Av. Alfredo Balena, 190
Belo Horizonte, MG – Brazil Postal code: 30130-100 lamber@uai.com.br
http://dx.doi.org/10.1590/1806-9282.63.06.532
Introduction: Thrombocytopenia is commonly found in patients living in highly endemic areas for Schistosoma mansoni. Recently, different degrees of liver steatosis
have also been associated with low platelet counts worldwide. We investigated the association of platelet counts with hepatosplenic schistosomiasis and with liver steatosis in an area of low prevalence of schistosomiasis in Brazil.
Method: Pains, a city in the state of Minas Gerais, Brazil, had a population of 8,307 inhabitants and a schistosomiasis prevalence of 8%. Four micro-areas comprising 1,045 inhabitants were selected for this study. Blood sample was collected and a complete blood count (CBC) was performed. Eighty-seven (87) patients had low platelet counts (group 1 – 8.3%) and 94 volunteers presenting normal CBC were randomized (group 2 – 8.9%). They underwent clinical and ultrasound examinations. Liver steatosis was determined as either present or absent using abdominal ultrasound. A spleen > 12 cm in length, measured by ultrasound (US), was considered to be increased. Data collected were analyzed using SPSS software version 19.0.
Results: Twenty-two patients (22/25.3%) in group 1 had liver steatosis compared with 11 volunteers (11.7%) in group 2 (p=0.02). Hepatosplenic schistosomiasis was diagnosed in two patients (p>0.05).
Conclusion: Thrombocytopenia was not a good marker of hepatosplenic schistosomiasis mansoni in a low prevalence area in Brazil. Liver steatosis was associated with thrombocytopenia in our study.
Keywords: fatty liver, Schistosoma mansoni, thrombocytopenia.
I
NTRODUCTIONIt has been estimated that 230 million people worldwide are infected with Schistosoma spp., with an additional 779
million at risk of infection. Currently, 2 to 6 million in-dividuals are considered infected in Brazil.1
Most of the infected individuals are asymptomatic, but 5 to 10% develop periportal liver fibrosis with portal hypertension and splenomegaly. Pathologically dense bands of fibrosis around the portal tract are typical of
Schistosoma mansoni.2
Schistosomal periportal fibrosis is usually assessed using imaging methods, and abdominal ultrasonography (US) has become the imaging technique of choice.3
How-ever, the identification of other non-invasive, inexpensive, and simple routine laboratory tests for use as surrogate markers is of interest.4-6
Recently, thrombocytopenia has been shown to iden-tify hepatosplenomegaly in Schistosoma-endemic areas and
moder-ate to high endemicity, showed that thrombocytopenia (platelets < 143,000/mm3) separated individuals with and
without hepatosplenic schistosomiasis.6
Liver steatosis (also called fatty liver) refers to the abnormal retention of lipids within a cell. Nonalcoholic fatty liver disease (NAFLD) is the most common cause of liver disease worldwide with prevalence estimates ranging from 25 to 45% in most studies.7,8 It covers a wide spectrum
of hepatic disorders including plain steatosis and steato-hepatitis (steatosis with inflammation) that can progress to liver fibrosis and cirrhosis.9,10
In the present study, we investigated the association of thrombocytopenia with hepatosplenic schistosomiasis and liver steatosis in an area of low prevalence of schis-tosomiasis in the Southeast of Brazil.
M
ETHODThis is a cross-sectional study carried out from July to November 2014, including residents of a lowly endemic area for Schistosoma mansoni.
Study location
Pains is a city with 8,307 inhabitants, distant 217 km from Belo Horizonte, capital of the state of Minas Gerais, Brazil. It has a total area of 418 km2, with a population
density of 19 people/km2 and human development index
(HDI) of 0.783.11
During the period of data collection, prevalence of schistosomiasis in this area was at 8% based on two quan-titative stool examinations. All inhabitants from four micro-regions, namely Alvorada, Vila Crispin, Matinha and Posto Agropecuário, totaling 1,637 individuals aged 9-92 years, were invited to participate in our study.
Study population
After signing an informed consent, a complete blood count (CBC) of 1,045 participants were performed. Eighty--seven (87) patients had low platelet counts (group 1 – 8.3%) and 94 randomly chosen volunteers had normal CBC (group 2 – 8.9%). Information on demographics, clinical examination and the results of the Kato-Katz stool ex-amination technique12 were stored in a data bank for data
analysis using SPSS 19.0 software.
Clinical examination
The 181 participants underwent anamnesis and physical examination carried out by one of the authors (JRL). Par-ticular attention was given to the abdominal examination, specifically the right hepatic lobe, which was examined
along the anterior axillary line, and the left hepatic lobe, examined along a line passing through the xiphoid process. The spleen was palpated and measured under the left costal margin with the patient in the dorsal decubitus position during deep inspiration.
Diagnosis of hepatosplenic schistosomiasis
The diagnosis was based on the following criteria: clinical evidence (hepatomegaly and splenomegaly) and ultrasound showing characteristic periportal fibrosis of the liver.
Ultrasound
All participants underwent abdominal US examination using a portable Medison Sonoace 1500 system with a 3.5-MHz probe (Samsung, Korea), being examined ac-cording to the protocol proposed by the World Health Organization (WHO) for US assessment of Schistosoma
--related morbidity.13 In our study, we used a spleen size
cut-off point of > 12 cm (longitudinal diameter).
Liver steatosis
US evaluation of fatty liver typically consists of a qualita-tive visual assessment of hepatic echogenicity, measure-ments of the difference between the liver and kidney in echo amplitude, evaluation of echo penetration into the deep portion of the liver, and determination of the clar-ity of blood vessel structures in the liver (Figure 1A). Ste-atosis was characterized as present or absent.14,15
Ethical considerations
This study was approved by the Human Research Ethical Board of the Federal University of São João del-Rei and of the Faculty of Medicine of the Federal University of Minas Gerais (number 856.022).
Statistical analysis
Questionnaire data and results of physical exams and US were transferred into an EpiData database, software version 3.1 (EpiDataAssociation, Odense, Denmark), and analyzed using the Statistical Package for Social Sci-ences (SPSS) 19.0 (SPSS, IBM Company, Chicago, IL). Categorical variables were compared using χ2 Pearson test. Whenever variables in the univariate analysis pre-sented p<0.20 they were included in the multivariate logistic regression analysis to evaluate the association with thrombocytopenia < 143,000/mm3. Multivariate
R
ESULTSThe demographic and clinical data of the participants are summarized in Table 1. All variables in the univariate analysis with p<0.20 were included in the model and age, gender, skin color, body mass index (BMI), general health status and liver steatosis were selected for further analy-sis. In the multivariate analysis, except for age, no sig-nificant correlation was detected, but a high frequency of liver steatosis called attention and we decided to investi-gate the association with other variables.
The association of liver steatosis with thrombocyto-penia and BMI was found significant in the multivariate logistic regression (Table 2).
D
ISCUSSIONOur study revealed a significant association of liver steato-sis with body mass index (BMI) (p<0.01) and thrombocy-topenia (p<0.02). Unexpectedly, no correlation was found between thrombocytopenia and hepatosplenic schistoso-miasis in this lowly endemic area for Schistosoma. In previous
studies, thrombocytopenia was a good marker of schisto-somiasis in highly endemic areas.5,7 This opens new ways of
approaching the subject. NAFLD was associated with throm-bocytopenia presently and has been described previously.16,17
Additionally, the association of steatosis with schistoso-miasis may aggravate liver disease, increasing the frequency of fibrosis, portal hypertension and liver cirrhosis.
In areas of high standard of living, the relation be-tween thrombocytopenia and liver steatosis is a possible explanation for the finding of low platelet counts in the blood. In a lowly endemic area for schistosomiasis, as in the present study, only 2 out of 181 (1.1%) individuals had typical periportal fibrosis caused by schistosomiasis and portal hypertension.
With the rising prevalence of obesity and metabolic disorders, liver steatosis has become a leading cause of chronic liver disease in Western countries. For example, steatosis is described in 46% of heavy drinkers, 40-69% of patients with diabetes and in 50-80% of the obese popula-tion.18,19 In Brazil, obesity is also a serious public health
problem. However, social classes are not homogeneously distributed in the country: there is an increasing group of high and middle class people in the southeast, and small-er areas of low income people in the northeast of Brazil.20
Pains is a city located in a high- and middle-income area and most people were well nourished (35.9% of the population was overweight or obese) by the time of our study, while in the northeast of Minas Gerais the preva-lence of overweight is low. The medical, educational and social assistance was superior in Pains than those offered in other poorer areas. Moreover, the Brazilian Program for Schistosomiasis Control has been active in the last 10 years in this city.
A number of studies demonstrated an association be-tween platelet counts and the severity of liver injury.21-25
Yoneda et al. and Ruiz-Arguelles et al. concluded that NAFLD should be considered as a cause of thrombocytopenia.16,17
Normally, the spleen stores one-third of the platelets that are produced in the body, maintaining a balance with the circulating platelets. Patients with cirrhosis, schistoso-miasis, portal hypertension or splenomegaly may have sig-nificant degrees of “apparent” thrombocytopenia (with or without leukopenia and anemia), but they rarely have clini-cal bleeding, since their total platelet mass is usually normal. Whether the presence of schistosomal periportal fi-brosis is associated with NAFLD would be an interesting topic for further study. In our hospital, one patient un-derwent surgical intervention for treatment of portal
FIGURE 1 A. Ultrasonography of liver steatosis. B. Hepatosplenic schistosomiasis and liver steatosis.
Liver steatosis
Renal cortex
A B
TABLE 1 Demographic and clinical variables of groups 1 (with thrombocytopenia) and 2 (without thrombocytopenia) in Brazil from July to November 2014.
Demographic variables Thrombocytopenia p-value*
No (n=94) Group 2
Yes (n=87) Group 1
Genre
Male 64 (68.1%) 48 (55.2%) 0.074
Age
Median 22.0 53.0 <0.001
Color
White 34 (36.2%) 46 (52.9%)
Black 27 (28.7%) 11 (12.6%) 0.078
Dark-skinned 33 (34%) 25 (28.7%)
Use of alcohol
Yes 26 (27.7%) 23 (26.4%) 0.823
No 65 (69.1%) 62 (71.3%)
Clinical variables Thrombocytopenia p-value*
No (n=94) Group 2
Yes (n=87) Group 1
General state
Good 92 (97.9%) 76 (87.4%) 0.019
Regular 1 (1.1%) 10 (11.5%)
Body mass index (BMI)
Median 22.1 24.8 <0.001
Hepatosplenic schistosomiasis
Yes 1 (1.0%) 1 (1.1%)
No 93 (98.9%) 86 (98.8%) 0.954
Liver steatosis
Yes 11 (11.7%) 22 (25.3%)
No 83 (88.3%) 65 (74.7%) 0.021
Gastrointestinal bleeding
Yes 6 (6.4%) 7 (8.0%) 0.679
No 86 (91.5%) 79 (90.8%)
Platelets
Median 218,000 123,000 0.958
Logistic regression χ2 Pearson test.
TABLE 2 Association between the independent variables body mass index (BMI) and thrombocytopenia and the presence of liver steatosis. Pains, state of Minas Gerais/Brazil from July to November 2014.
Independent variables Odds ratio (95CI) p-value*
BMI 1.21 (1.2-1.8) <0.001
Thrombocytopenia < 143,000/mm3 16.66 (1.4-93.2) 0.024
hypertension, and a photograph documented the asso-ciation during the surgical procedure (Figure 1B).
The association of thrombocytopenia with hepato-splenic schistosomiasis motivated our study. Our inten-tion was to investigate the soundness of using thrombo-cytopenia as a marker of hepatosplenic schistosomiasis. In the end, thrombocytopenia was, in fact, associated with NAFLD. A possible explanation for disagreement is that the association of thrombocytopenia with hepatosplenic schistosomiasis previously occurred in highly endemic areas,6 while, presently, our investigation was performed
in an area of low prevalence (8%) and low morbidity (two patients with hepatosplenic schistosomiasis). We conclude that thrombocytopenia is a good marker of liver steatosis in this lowly endemic area for schistosomiasis. The as-sociation of schistosomiasis with thrombocytopenia was not confirmed in the present study.
A
CKNOWLEDGMENTSWe thank Mrs. Virgina Vilela Rabelo, Municipal Secretary of Pains and Miss Sandra Costa Drummond (Secretary of Minas Gerais State) for their help during the development of all stages of this study. We also acknowledge Mr. Fran-cisco for his technical assistance. We thanks the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (Fapemig, Brazil) and Conselho Nacional de Desenvolvimento Cientí-fico e Tecnológico of the Ministry of Science, Technology and Innovation of Brazil (CNPq) for funding this work.
C
ONFLICT OF INTERESTThe authors declare no conflict of interest.
R
ESUMOTrombocitopenia como marcador de esteatose hepática em áreas de baixa endemicidade de esquistossomose mansoni
Introdução: Trombocitopenia é um achado comum em pacientes que residem em áreas com alta endemicidade de esquistossomose mansônica. Recentemente, diferentes graus de esteatose hepática também têm sido associados a níveis baixos de plaquetas em todo o mundo. Investigamos a associação de níveis séricos de plaquetas com a forma grave da esquistossomose e com esteatose hepática em área de baixa prevalência de esquistossomose no Brasil.
Método: Pains, cidade localizada no estado de Minas Gerais/Brasil, tem população de 8.307 habitantes e preva-lência de esquistossomose de 8%. Em quatro microáreas dessa região, 1.045 habitantes foram avaliados para o es-tudo. Amostra de sangue foi coletada para realização do
hemograma. Oitenta e sete (87) pessoas com níveis baixos de plaquetas formaram o grupo 1 (8,3%), e 94 voluntários com hemograma normal foram randomizados para com-por o grupo 2 (8,9%). Todos os participantes dos grupos 1 e 2 foram submetidos a exame clínico e ultrassonografia (US) abdominal. Esteatose hepática foi caracterizada como presente ou ausente pela ultrassonografia (US) abdominal. Baços com mais de 12 cm de comprimento à US foram considerados aumentados. Os dados coletados foram analisados pelo programa de estatística SPSS 19.0.
Resultados: Vinte e dois (22) indivíduos do grupo 1 (25,3%) e 11 do grupo 2 apresentaram esteatose hepática (11,7%) (p=0,02). Esquistossomose hepatoesplênica foi diagnosti-cada em dois pacientes (p>0,05).
Conclusão: Trombocitopenia não foi um bom marcador de esquistossomose mansônica hepatoesplênica em área de baixa prevalência da esquistossomose no Brasil. Esteatose hepática foi associada com trombocitopenia no presente estudo.
Palavras-chave: esteatose hepática, Schistosoma mansoni,
trombocitopenia.
R
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